skylab_utils: Do a shallow clone to save time.

BUG=chromium:842754
TEST=manual

Change-Id: I92f7dedda150b2fe733d06d5a762d8458c9902fa
Reviewed-on: https://chromium-review.googlesource.com/1112621
Commit-Ready: Prathmesh Prabhu <[email protected]>
Tested-by: Prathmesh Prabhu <[email protected]>
Reviewed-by: Jacob Kopczynski <[email protected]>
diff --git a/cli/skylab_utils.py b/cli/skylab_utils.py
index 60a3dfd..0b5de24 100644
--- a/cli/skylab_utils.py
+++ b/cli/skylab_utils.py
@@ -127,7 +127,7 @@
             self.git_repo.pull()
         else:
             logging.info('No inventory repo was found, start cloning.')
-            self.git_repo.clone()
+            self.git_repo.clone(shallow=True)
 
 
     def get_data_dir(self, data_subdir='skylab'):